[Python-Dev] Re: rexec.py unuseable

[Luke Kenneth Casson Leighton]

On Tue, Dec 16, 2003 at 10:04:40PM +0100, Jack Jansen wrote:
> 
> On 16-dec-03, at 17:16, Luke Kenneth Casson Leighton wrote:
> >>Luke replied:
> >>>capabilities, acls, schmapabilities, same thiiing :)
> >>
> >>No... they're not. Read the thread I mentioned above, or read this,
> >>and some of the other documentation for the language E:
> >>
> >>  http://www.erights.org/elib/capability/ode/ode-capabilities.html
> >
> > no offense intended: i'll read that later, i'm running out of time.
> >
> > without going into too many definitions, consider what i am advocating
> > to be _like_ an access control list but instead to be a capabilities
> > control list, instead.
> 
> The distinction between capabilities and ACLs is really important, 
> because
> they are almost each others opposite. With capabilities you have an 
> (unforgable)
> right to do something and no-one cares about your identity, with ACLs 
> you have
> an unforgable identity which is checked against the ACL.

 i'd like to introduce you to a new concept which is idential
 in form to an ACL - access control list - except that instead
 of "users" being allowed or denied access to perform certain
 operations you have instead _functions_ being allowed or
 denied access to perform certain operations.

 perhaps a better way to explain the concept to you is to introduce
 a concept called "qualified" capabilities, where what you know of
 as capabilities is "qualified" on a per-function (that's per-caller)
 basis.

 obviously, any object (by object i am referring generically to
 classes, class instances, functions, modules, absolutely anything)
 can potentially have many "callers", consequently it is necessary
 to create a _list_ of qualified capabilities, and for the
 relevant QCap in that list to be looked up and applied as needed.

 where, of course, the special wildcard name 'all functions' applies
 to _all_ callers.


 which makes what i am proposing to be named
 
 "QCCL" - qualified-capabilities control list.

 yuk :)

 l.